Figure 4
Comparisons of codon usage in S. salmonicida and G. lamblia. A and B: The effective number of codons, Nc', plotted against the synonymous G+C content in the third codon position (GC3s) of 1153 S. salmonicida genes (A) and 438 homologs in G. lamblia (B). Genes are represented by different colors and symbols according to the number of times they were sampled within the EST data. Genes identified to be involved in gene transfer and are shared with G. lamblia (LGT Diplo), or unique to S. salmonicida (LGT Spiro), are indicated by black and red squares, respectively (see Additional file 3). If the observed codon usage pattern is more uniform than expected by chance, the Nc' value is set to 61 [75, 117]. C and D: Correspondence analysis of the relative synonymous codon usage (RSCU) values for the same genes as in A and B for S. salmonicida (C) and G. lamblia (D). The candidate LGTs unique to S. salmonicida, and shared with G. lamblia, are indicated by red and black open squares, respectively.